A rice cake which is a Korean traditional food based on rice, is classified by nonglutinous rice cake and glutinous rice cake, in which glutinous rice can be used to make a various of cake such as Ingeolmi (i.e. glutinous rice cake covered with bean flour), well-nutrished glutinous rice cake etc., because it can be easily digested and be kept with softness for a long time without hardening compared to nonglutinous rice. A traditional production method of rice cake consists of soaking a rice into water and powdering the rice and then putting the rice powder through sieve and steaming the sieved rice powder with steamer and separately preparing a nut or flour for powdering rice cake and thus it is difficult and complicate to make rice cake at home.
Since a structure of glutinous rice starch is constructed with only amylopectin having branched structure, in which various of glucose chain are connected with α-1,4 bonding to glucose chain back bone of α-1,6 bond, glutinous rice cake, different from nonglutinous rice cake, has a tendency to stretch without maintaining shape after heating or reheating prepared rice cake. When glutinous rice cake is prepared at a specialty store or a home, glutinous rice is steamed in a steamer and shaped in hot state and then cut and eaten after getting cold and thus shape retainability of the cooked rice cake is beside of the question. However, because the premix composition of glutinous rice cake of the present invention for baking in microwave oven is for the convenience of a consumer, shape retainability is very important.
With regard to the prior art for rice powder and premix of rice cake, the Published Korean Patent Application No. 2002-0050656 disclosed a method for preparing rice cake in which the rice cake was prepared with rice powder made by soaking a rice in water and grinding and then completely drying, and cereal flour made by steaming and grinding. However, the above invention only relates to the rice powder made by grinding rice and drying and the dried cereal flour, there is still complicate problem that water is added to the rice powder and the cereal flour and then the mixture is steamed in a steamer.
The Published Korean Patent Application No. 2003-0072094 disclosed a premix composition comprising as a main component wheat flour for rice cake or noodles containing resistant starch.
The Published Korean Patent Application No. 2006-0024118 disclosed a quality improving agent for rice cake and a premix of rice powder comprising the same, in which the quality improving agent for rice cake comprises α- and β-denatured starch at ratio of 17:83 to 75:25 and the premix of rice powder comprises 60 to 80 wt % of the dried rice powder and 20 to 40 wt % of the quality improving agent, and the premix is characterized in inhibiting aging as containing the denatured starch compared to that of made by 100% unglutinous rice powder. The premix is for the conventional method for preparing rice cake in which water is added to and mixed with rice powder and the mixture is shaped and steamed.
In addition, the Published Korean Patent Application No. 2007-0007652 disclosed a composition of instant rice cake for baking in microwave oven and method for preparing the same in which a premix of rice cake for baking in microwave oven is prepared by the process of washing unglutinous rice to remove impurities and soaking it into water and going through the steps of dehydrating, grinding, drying, re-grinding and drying and then selecting to the grain size, and using the selected rice powder to make the premix. The above invention disclosed the premix of rice cake for baking in microwave oven, however, the premix has the starch damage of 5 to 10% and use unglutinous rice having grain size of 80 to 200 mesh and it has defects that the rice cake prepared by the premix is maintained only for 2 hours after cooking without using inhibitor of aging and is also impossible to distribute at room temperature due to the possibility of the propagation of microorganism or a change in quality as it has water content of above 25%.
Accordingly, as considering the above facts, the present inventors accomplish the present invention by confirming that a premix composition of glutinous rice cake can be prepared to have a good shape retainability after heating and to maintain softness for 24 hours without adding inhibitor of aging and to distribute for above 6 months at room temperature with glutinous rice of water content of below 15% by using glutinous rice powder having 200 to 400 μm of average grain size and comprising less than 5 wt % of glutinous rice powder of below 200 mesh and 40 to 70 wt % of glutinous rice powder of 200 to 400 mesh.
The present invention is different from the prior arts and have advantages to provide convenience that glutinous rice cake similar to that of available in commercial specialty store can be cooked only by microwave oven at a home by using glutinous rice which has the controlled grain size obtained by grinding via understanding properties of glutinous rice.